Many people hang up on telemarketers, but others will listen politely to their pitches even if they are not interested in the product. telemarketers know that anyone who agrees to listen to a pitch is more likely to buy the product, as they slowly build up to their real request, to the

This is thanks to the foot-in-the-door phenomenon. This phenomenon works by first getting someone to agree or comply with something that is a small and not too tedious task (here, this would be the agreement to stay on the phone and listen to the pitch). Next, once the small task is completed, the person is more likely to agree to a much larger task (here, whatever the telemarketer is selling).